qemuBuildNumaArgStr: Discard def->cpu check

In the function at one place we check if def->cpu is NULL prior
to accessing def->cpu->ncells. Then, later in the code,
def->cpu->ncells is accessed directly, without the check. This
makes coverity unhappy, because the first check makes it think
def->cpu can be NULL. However, the function is not called if
def->cpu is NULL. Therefore, remove the first check and hopefully
make coverity cheer again.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_command.c

@@ -6594,7 +6594,7 @@ qemuBuildNumaArgStr(virQEMUDriverConfigPtr cfg,
             continue;
         }
 
-        if (def->cpu && def->cpu->ncells) {
+        if (def->cpu->ncells) {
             /* Fortunately, we allow only guest NUMA nodes to be continuous
              * starting from zero. */
             pos = def->cpu->ncells - 1;